Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

In a method and apparatus for influencing transverse dynamics of a
vehicle, for a chassis intervention is carried out when an intervention
condition is met. The intervention condition is met when the value of a
determined transverse dynamics disturbance variable is higher than a
disturbance variable threshold value, and when one or a group of the
following criteria is met: the longitudinal speed of the vehicle is
higher than a longitudinal speed threshold value of the vehicle; the
sensorially detected actual yaw rate is lower than or equal to a
calculated current yaw rate; a braking torque variable describing a
braking torque and caused by braking by the driver is lower than or equal
to a braking torque threshold value; a spring variable describing the
current spring path of a chassis spring of a vehicle wheel is lower than
or equal to a spring path threshold value; a differential spring variable
describing the difference between the current spring paths of the two
chassis springs of a vehicle axle is lower than or equal to a
differential spring path threshold value; and a slip difference variable
describing the slip difference between two vehicle wheels is lower than
or equal to a slip differential threshold value.

Claims:

1.-13. (canceled)

14. A method for influencing the transverse dynamics of a vehicle, said
method comprising:detecting a transverse dynamics disturbance variable
acting on the vehicle;checking whether a preset intervention condition is
fulfilled; andif an intervention condition is fulfilled, carrying out a
chassis intervention to influence the transverse vehicle dynamics;wherein
the intervention condition is fulfilled when the magnitude of the
determined transverse dynamics disturbance variable is higher than a
disturbance variable threshold value, and when one or a group of the
following criteria is fulfilled--longitudinal speed of the vehicle is
higher than a longitudinal speed threshold value of the vehicle;a sensor
detected actual yaw rate is lower than or equal to a calculated current
yaw rate;a braking torque variable describing a braking torque caused by
braking intervention by the driver is lower than or equal to a braking
torque threshold value;a spring variable describing a current spring path
of a chassis spring of a vehicle wheel is lower than or equal to a spring
path threshold value;a differential spring variable describing the
difference between current spring paths of two chassis springs of a
vehicle axle is lower than or equal to a differential spring path
threshold value; anda slip difference variable describing the slip
difference between two vehicle wheels is lower than or equal to a slip
differential threshold value.

15. The method according to claim 14, wherein detecting said transverse
dynamics disturbance comprises detecting said transverse dynamics
disturbance on a chassis of the vehicle.

16. The method according to claim 14, wherein the intervention condition
is fulfilled if at least one of the following is true:the amount of the
steering wheel angle is lower than or equal to a steering angle threshold
value; andthe amount of the steering wheel angle speed is lower than or
equal to a steering angle speed threshold value.

17. The method according to claim 14, wherein the intervention condition
is fulfilled when stationary transverse acceleration of the vehicle is
smaller than or equal to a transverse acceleration threshold value.

18. The method according to claim 15, wherein:a lateral wind acting on the
chassis of the vehicle by means of the disturbance variable determination
device is recognized; anda corresponding disturbance of the transverse
dynamics of the vehicle is compensated at least partially.

19. The method according to claim 14, wherein an intervention
determination value is determined, which describes at least one of:the
amount of the transverse dynamic disturbance variable;the amount of the
yaw rate to be adjusted by means of the transverse dynamics disturbance
variable for compensating the transverse disturbance; andthe amount of
another variable correlating with one of the two variables.

20. The method according to claim 14, wherein said chassis intervention
comprises at least one of:a braking intervention at least one vehicle
wheel;an influence of the wheel loads at least one vehicle wheel;an
influencing of the servo torque of a servo motor of a servo steering
system; anda change of at least one wheel drive torque at least one
vehicle wheel.

21. The method according to claim 19, whereinsaid chassis intervention
comprises at least one of,a braking intervention at least one vehicle
wheel;an influence of the wheel loads at least one vehicle wheel;an
influencing of the servo torque of a servo motor of a servo steering
system; anda change of at least one wheel drive torque at least one
vehicle wheel; andwhen a magnitude of the intervention determination
value is below a lower threshold value, only one of the wheels,
especially one of the non-steerable wheels is braked via the respective
associated braking device

22. The method according to claim 19, wherein:said chassis intervention
comprises at least one of:a braking intervention at least one vehicle
wheel;an influence of the wheel loads at least one vehicle wheel;an
influencing of the servo torque of a servo motor of a servo steering
system; anda change of at least one wheel drive torque at least one
vehicle wheel;the intervention determination value is greater than or
equal to the lower threshold value, and lower than an upper threshold
value, only one of the steerable wheels is braked at the front axle via
the respective associated braking device.

23. The method according to claim 19, wherein:said chassis intervention
comprises at least one of:a braking intervention at least one vehicle
wheel;an influence of the wheel loads at least one vehicle wheel;an
influencing of the servo torque of a servo motor of a servo steering
system; anda change of at least one wheel drive torque at least one
vehicle wheel;if the intervention determination value is greater than or
equal to the upper threshold value, both wheels of the same vehicle side
are braked via the respective associated braking device.

24. The method according to claim 19, wherein said chassis intervention
comprises at least one of,a braking intervention at least one vehicle
wheel;an influence of the wheel loads at least one vehicle wheel;an
influencing of the servo torque of a servo motor of a servo steering
system; anda change of at least one wheel drive torque at least one
vehicle wheel;both wheels of the same vehicle side are braked via
associated braking devices; andbraking force distribution between a
steerable wheel and a corresponding non-steerable wheel of the same
vehicle side is parameter-dependent, and is preset in dependence on the
vehicle and/or can be adjusted according to the drive situation.

25. The method according to claim 14, wherein a chassis intervention which
is triggered after fulfillment of the intervention condition is ended, if
at least one of the following is true:a braking torque variable
describing the braking torque caused by the driver is higher than a
braking torque threshold value;the magnitude of a vehicle steering angle
is greater than a steering angle threshold value; andthe magnitude of
steering angle speed is greater than a steering angle speed threshold
value.

26. The method according to claim 14, wherein the transverse dynamics
disturbance value is filtered by a high pass filter prior to checking the
intervention condition.

27. Apparatus for influencing transverse dynamics of a vehicle, said
apparatus comprising:a disturbance variable determination device for
determining the transverse dynamics disturbance variable acting on the
vehicle;a checking device which determines whether a preset intervention
condition is fulfilled; anda device which implements a chassis
intervention to influence the transverse dynamics when the intervention
condition is fulfilled;wherein, the intervention condition is determined
to be fulfilled when a magnitude of the determined transverse dynamics
disturbance variable is higher than a disturbance variable threshold
value, and when one or a group of the following criteria is
fulfilled--longitudinal speed of the vehicle is higher than a
longitudinal speed threshold value of the vehicle;a sensor detected
actual yaw rate is lower than or equal to a calculated current yaw rate;a
braking torque variable describing a braking torque caused by braking
interventions by the driver is lower than or equal to a braking torque
threshold value;a spring variable describing a current spring path of a
chassis spring of a vehicle wheel is lower than or equal to a spring path
threshold value;a differential spring variable describing the difference
between current spring paths of two chassis springs of a vehicle axle is
lower than or equal to a differential spring path threshold value; anda
slip difference variable describing the slip difference between two
vehicle wheels is lower than or equal to a slip differential threshold
value.

Description:

[0001]This application is a national stage of PCT International
Application No. PCT/EP20081004458, filed Jun. 4, 2008, which claims
priority under 35 §119 to German Patent Application No. 10 2007 029
605.5, filed Jun. 27, 2007, the entire disclosure of which is herein
expressly incorporated by reference.

BACKGROUND AND SUMMARY OF THE INVENTION

[0002]The invention relates to a device for influencing the transverse
dynamics of a vehicle, especially a motor vehicle, wherein a transverse
dynamics disturbance variable acting on the vehicle (and especially the
chassis) is determined by means of a disturbance variable determination
device, and a chassis intervention braking intervention is brought about.

[0003]The present invention further relates to a transverse dynamics
influencing device for a vehicle, especially a motor vehicle, with a
disturbance variable determination device for determining a transverse
dynamics disturbance variable acting on the vehicle and especially the
chassis.

[0004]To increase driving safety when driving a vehicle, such as a motor
vehicle, it is desirable to assist the driver with regard to suddenly
occurring influences or disturbances of the vehicle transverse dynamics.
Such disturbances of the vehicle transverse dynamics can especially occur
with a strong lateral wind in connection with lateral wind blasts.

[0005]In a device for influencing the transverse dynamics of a motor
vehicle in the form of a parallel drive regulation system disclosed in
German patent document DE 40 14 365 A1, the distance to a guide device is
measured during a parallel drive, and with distance changes (for example,
due to a lateral wind), the driving direction is corrected by braking.
However, the described device can only be used when the mentioned guide
device is present.

[0006]In a method and a apparatus for influencing the transverse dynamics
of a vehicle disclosed in International Patent. Document WO 2006/037678
A1, a determined disturbance of the transverse dynamics is dealt with by
a change of the wheel load of at least one vehicle wheel.

[0007]One object of the invention, starting from a method and a device of
the above-mentioned type, is to provide a method and apparatus that
increases driving safety in different driving situations.

[0008]This and other objects and advantages are achieved by the driving
assistance method and apparatus according to the invention, in which, the
driver needs not react with a (possibly uncontrolled) steering movement
response to a sudden disturbance of the vehicle transverse dynamics;
rather, an automatic compensation or correction of the disturbance is
provided, so that, the driving safety is increased. This advantageous
result is achieved according to the invention without depending on
external devices, such as the above-mentioned guide device. Also, a
chassis intervention as defined below) is triggered only if the
intervention condition is fulfilled. In this manner, driving situations
are excluded in which a chassis intervention (especially a braking
intervention) would not increase driving safety. Moreover, chassis
interventions which could reduce the driving safety are not carried out.

[0009]The intervention condition is fulfilled, if one of the given
criteria or a group of several of the given criteria is fulfilled:
[0010]the amount of the determined transverse disturbance variable is
larger than a disturbance variable threshold value, whereby braking
interventions with low transverse dynamics disturbances are avoided:
[0011]the longitudinal speed of the vehicle is higher than a longitudinal
speed threshold value, whereby braking interventions in an uncritical
situation with a lower longitudinal vehicle speed can be avoided:
[0012]the sensorially detected actual yaw rate is lower than or equal to
a current yaw rate calculated by means of for example the actual
transverse acceleration, to avoid unnecessary braking interventions in
situations where the occurring yaw rate or transverse acceleration was
not mainly caused by the transverse dynamics disturbance variable;
[0013]a braking torque variable describing a braking torque and caused by
braking by the driver is lower than or equal to a braking torque
threshold value, so that with braking processes with large braking
torques (such as, for example, emergency or full braking processes),
automatic one-sided braking interventions can be avoided; [0014]a spring
path variable describing the current spring path of a chassis spring of a
vehicle wheel is lower than or equal to a spring path threshold value;
[0015]a differential spring path variable describing the difference
between the current spring paths of the two chassis springs of a vehicle
axle is lower than or equal to a differential spring path threshold
value; and/or [0016]a slip difference variable describing the slip
difference between two vehicle wheels is lower than or equal to a slip
differential threshold value.

[0017]The intervention condition is advantageously fulfilled only if the
amount of the steering wheel angle is lower than or equal to a steering
angle threshold value and/or if the amount of the steering angle speed is
lower than or equal to a steering angle speed threshold value. In this
manner, a chassis intervention with dynamic steering wheel rotations by
the driver can be avoided, so as not to endanger the driving safety.

[0018]Furthermore, the intervention condition can be fulfilled only if the
amount of the stationary transverse acceleration is lower than or equal
to a transverse acceleration threshold value, Chassis interventions
during the driving of dynamic maneuvers (for example, when driving
through turns with correspondingly small turning radii) are avoided in
this manner. A longitudinal speed-dependent steering wheel limit is thus
achieved.

[0019]It is also possible to recognize a lateral wind acting on the
chassis of the vehicle and to compensate at least partially a
corresponding disturbance of the transverse dynamics by the chassis
intervention to increase the driving safety in the case of an occurring
lateral wind.

[0020]The chassis intervention can be any one or more of the following:
[0021]a braking intervention at one or several wheels; [0022]an influence
of the wheel loads at one or several wheels; [0023]an influence of the
servo torque of a servo motor of a servo steering system; and [0024]a
change of one or several wheel drive torques at one or several wheels.

[0025]Furthermore, an "interference determination value" can be
determined, which describes the amount of the transverse dynamics
disturbance variable or the amount of the yaw torque, determined by means
of the transverse dynamics disturbance variable, to be adjusted in order
to compensate for the transverse disturbance, with a variable correlating
the two variables. Thereby, with magnitudes of the intervention
determination value below a lower threshold value, only one of the wheels
(especially one of the non-steerable wheels) can be braked via an
associated braking device. With amounts of the intervention determination
value larger than or equal to the lower threshold value, and lower than
an upper threshold value, only one of the steerable wheels can be braked
at the front axle, via the associated braking device. Furthermore, with
amounts of the intervention determination value larger than or equal to
the upper threshold value, both wheels of the same vehicle side can be
braked via the respective associated braking devices. In this manner,
brake intervention can be adapted to the intensity of the transverse
dynamics disturbance caused by the transverse dynamics disturbance
variable.

[0026]Further, there is also the possibility of braking both wheels of the
same vehicle side via the respective associated braking devices, with the
braking force distribution between the steerable wheel and the
corresponding non-steerable wheel being parameter-dependent. In
particular, it can be given in a vehicle-dependent manner and/or adjusted
in a driving situation-dependent manner.

[0027]Other objects, advantages and novel features of the present
invention will become apparent from the following detailed description of
the invention when considered in conjunction with the accompanying
drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028]FIG. 1 is a schematic depiction of a motor vehicle with a design of
the device according to the invention;

[0029]FIG. 2 is a block diagram that depicts a progress of an embodiment
of the method according to the invention;

[0030]FIG. 3 is a block diagram that illustrates checking of several
criteria of an intervention condition in the validity block VAL of FIG.
2; and

[0031]FIG. 4 is a block diagram that illustrates checking of further
criteria of an intervention condition in switch-off bock OFF of FIG. 2.

[0032]FIG. 1 is a schematic depiction of a motor vehicle with an
embodiment of the device according to the invention. The motor vehicle 1
has four wheels 2.1-2.4, each being an associated braking unit 3.1-3.4
operatively connected to it. Each of the braking units 3.1-3.4 is formed
for braking of the wheel 2.1-2.4 respectively associated therewith, and
can be activated individually, independent of the respective other
braking units. Thereby, different braking forces or braking actions can
be achieved at the single wheels 2.1-2.4. (A corresponding activation of
the braking unit with 2.1-2.4 is also called "braking intervention".)

[0033]For activating the braking units 3.1-3.4, a braking force activation
unit 4 is provided according to the invention, which is coupled in signal
communication with the braking units 3.1-3.4 The braking force activation
unit 4 itself is coupled in signal communication with a control unit 5,
which has a disturbance variable determination device 5.1 (also referred
to herein as a "disturbance variable viewer"), and a checking device 5.2.
The control unit 5 is connected to a number of sensors 6.1-6.n.

[0034]The sensors 6.1-6.n serve to determine drive-dynamic actual
variables of the vehicle 1, such as an actual yaw rate, a longitudinal
vehicle speed, a steering wheel angle, a steering angle or an actual
transverse acceleration. Corresponding sensor signals in SS1-SSn are
transferred by the sensors 6.1-6.n to the control unit 5 and thus to the
disturbance variable determination device 5.1 and the checking device.

[0035]The disturbance variable determination device 5.1 determines a
transverse dynamics disturbance variable of the vehicle from the actual
variables of the vehicle 1, as is explained in detail in the German
patent application 10 2004 017 638. In this manner, the disturbance
variable determination device 5.1 can be used especially for determining
the disturbance effect of lateral wind SW acting on the vehicle 1 or its
chassis and the influence of the vehicle transverse dynamics caused
thereby. The German patent application 10 2004 017 638 is insofar
referred to explicitly.

[0036]The disturbance variable determination device 5.1 generates a
disturbance variable signal SGS, which is transmitted to the checking
device 5.2. The checking device 5.2, determines by means of a given
intervention condition, if a braking intervention shall be brought about
that counteracts the transverse dynamics disturbance. A corresponding
intervention signal BES is transferred to the braking force activation
device 4, which activates at least one of the braking units 3.1-3.4 by
means of corresponding braking force activation signals BKAS1-BKAS4, in
dependence on the intervention signal BES. The braking force activation
signals are also transmitted to the control unit 5 and especially the
disturbance variable determination device 5.1, to be able to consider the
braking torque caused at one vehicle side and the influence of the yaw
movement of the vehicle resulting therefrom, during the determination of
the transverse dynamic disturbance variable.

[0037]The braking intervention is basically carried out at a wheel 2.1,
2.4 or 2.2, 2.3 of a vehicle side to generate a yaw torque
counter-directed to the transverse disturbance. So as to make the braking
intervention as comfortable as possible for the driver, only the
corresponding non-steerable wheel 2.1 or 2.2 can be braked exclusively,
or at least in a first braking intervention stage at the rear axle of the
vehicle, such that possible noticeable feedbacks at the steering wheel of
the vehicle 1 remain as low as possible. How strong possible feedbacks on
the steering wheel are during the wheel-individual braking of a steerable
wheel 2.3 or 2.4 depends on the vehicle type and its chassis design.
Whether the braking intervention takes place at a steerable wheel 2.3 or
2.4 and/or at a non-steerable wheel 2.1 or 2.2, is adapted individually
to the vehicle type. With vehicle types where, during braking of a
steerable wheel 2.3 or 2.4, only small feedbacks occur at the steering
wheel, the steerable wheel 2.3 or 2.4 of the same vehicle side can be
braked alternatively or in addition to the non-steerable rear wheel 2.1
or 2.2, to compensate for transverse disturbances.

[0038]It is thus possible to design the braking intervention in such a
manner that the wheels 2.1, 2.4 or 2.2, 2.3 of one vehicle side are
braked simultaneously. The braking force distribution between the
steerable front wheel 2.3 or 2.4 and the rear wheel 2.2 or 2.1 on this
vehicle side can be preset dependent upon the vehicle and/or adjusted in
dependence on the driving situation. The braking force distribution
between the steerable front wheel 2.3 or 2.4 and the non-steerable rear
wheel 2.2 or 2.1 can for example be considered by parameters such as the
amount of the transverse dynamics disturbance variable, the steering
angle, the brake torque caused on the vehicle side and the influence of
the yaw movement of the vehicle resulting therefrom during the
determination of the transverse dynamic disturbance variable.

[0039]An intervention determination value, which describes the amount of
the transverse dynamics disturbance variable or the amount of the yaw
torque to be adjusted, can be determined in the checking device 5.2 using
the transverse dynamics disturbance variable for compensating the
transverse disturbance, or the amount of another variable correlating
with one of the two variables. A multi-stage braking intervention can
then take place as a function of the intervention determination value,
wherein the following possibilities result: [0040]a) The intervention
determination value exceeds the intervention threshold value and is
smaller than a preset lower threshold value: First, only one wheel 2.1 or
2.2 or 2.3 or 2.4 is braked (preferably, a non-steerable wheel 2.3 or
2.4). Only if this braking intervention carried out exclusively at one of
the wheels 2.1 or 2.2 or 2.3 or 2.4 does not show a sufficient effect,
the further wheel 2.1 or 2.2 or 2.3 or 2.4 of the same vehicle side is
braked. [0041]b) If the intervention determination value is higher than
or equal to the lower threshold value, both wheels 2.1, 2.4 or 2.2, 2.3
of the same vehicle side are braked to reduce the transverse dynamics
influence of the vehicle 1 by the transverse dynamics and to ensure a
high driving safety. [0042]c) In a further development, it is also
possible to provide three intervention stages: [0043]With an
intervention determination value higher than the intervention threshold
value and lower than the lower threshold value, only one of the
non-steerable wheels 2.1 or 2.2 is braked via the respective associated
braking devices 3.1 or 3.2. [0044]With an intervention determination
value higher than or equal to the lower threshold value and smaller than
an upper threshold value, only one of the steerable wheels 2.3 or 2.4 is
braked at the front axle via the respective associated braking device 3.3
or 3.4. [0045]With an intervention determination value higher than or
equal to the upper threshold value, both wheels 2.1, 2.4 or 2.2, 2.3 of
the same vehicle side are braked by the respective associated braking
devices 3.1, 3.4 or 3.2, 3.3.

[0046]If a lateral wind blast SW (FIG. 1) acts, for example, on the
chassis of the vehicle 1 seen from the right in the drive direction, the
right rear wheel 2.2 and/or the right front wheel 2.3 can be braked, so
as to generate a yaw torque on the vehicle 1 around its vertical axis in
the clockwise direction. With a lateral wind acting on the vehicle 1 from
the left, the directions are exactly reversed, wherein the left front
wheel 2.4 and or the left rear wheel 2.1 are then braked.

[0047]The disturbance of the transverse dynamics by the lateral wind SW is
at least compensated partially by the braking intervention. The
disturbance determination device 5 and/or the braking force activation
device 4 is/are formed for this purpose to determine a necessary braking
force at a wheel or several wheels 2.1-2.4 of the vehicle 1, so as to
compensate the occurred disturbance of the vehicle transverse dynamics
correspondingly as already mentioned.

[0048]The driver of the vehicle 1 is thus assisted during the compensation
of a disturbance of the vehicle transverse dynamics, such as for example
a lateral wind blast. The disturbance of the transverse dynamics is thus
reduced automatically or completely compensated, helping to increase
driving safety.

[0049]In the following, an embodiment of the method according to the
invention is explained with references to FIG. 2. FIG. 2 is a block
diagram of an embodiment of the method according to the invention for
influencing the transverse dynamics of a vehicle, especially the motor
vehicle 1 according to FIG. 1.

[0050]The method according to the invention starts with the determination
of the transverse dynamics disturbance variable FSW in a viewer block
OBS, based on the of the drive-dynamic actual values of the vehicle
measured by means of the sensors 6.1 to 6.n, and on the braking force
activation signals BKAS1-BKAS4. The method for determining the transverse
dynamics disturbance variable used in the viewer block OBS is described
in German patent application DE 10 2004 017 638 A1, which is referred to
in this connection.

[0051]The transverse dynamics disturbance variable FSW, determined in this
manner by means of the viewer block OBS, is subsequently high pass
filtered in a high pass filter HP to filter out stationary parts of the
transverse dynamics disturbance variable, which are not considered in the
following method. (Only dynamic parts of the transverse dynamics
disturbance variable FSW are considered in the further method.) The
highpass filter HP generates the high pass filtered transverse dynamics
disturbance variable, which corresponds to the disturbance variable
signal SGS in the present case, and is transferred to the checking device
5.2 of the control unit.

[0052]In the checking device 5.2 it is checked if a preset intervention
condition is fulfilled. The intervention condition has several criteria
with the embodiment of the method, which for example respectively have to
be fulfilled individually to fulfill the intervention condition. These
criteria serve to exclude drive situations, in which no automatic braking
intervention is to be caused.

[0053]It is checked in a hysteresis block as a first criterion, whether
the disturbance variable signal SGS (that is, the high pass filtered
transverse dynamics disturbance variable) is larger than a preset
activation threshold value, or is smaller than a deactivation threshold
value. The activation threshold value is larger than the deactivation
threshold value, so that a hysteresis is formed. If the disturbance
variable signal is larger than the activation threshold value, a first
flag F1=1 is set. If, however, the disturbance variable signal SGS is
smaller than the deactivation threshold value, the first flag K1=0 is
set: [0054]SGS>activation threshold value F1=1 or
[0055]SGS<deactivation threshold value F1=0.

[0056]Further criteria are checked in a validity block VAL, for example
eight criteria K2 to K9, via which the current drive situation is judged,
as is depicted in detail in FIG. 3 schematically. The following criteria
are checked to determine whether:

[0057]Second Criterion K2: [0058]the amount of the steering wheel angle
δ is smaller than or equal to the steering wheel threshold value
δs;

[0059]Third Criterion K3: [0060]the amount of the steering wheel angle
speed {dot over (δ)} is smaller than or equal to a steering wheel
speed threshold value {dot over (δ)}s;

[0063]Fifth Criterion K5: [0064]the sensorially detected actual yaw rate
{dot over (Ψ)} is lower than or equal to a calculated current yaw
rate {dot over (Ψ)}mod (calculated on the basis of a given
vehicle model), which describes the connection between the transverse
acceleration and yaw rate, by means of the measures actual transverse
acceleration ay;

[0065]Sixth Criterion K6: [0066]the amount of the stationary transverse
acceleration ay,stat is smaller than or equal to a transverse
acceleration threshold value ay,stat,s;

[0067]Seventh Criterion K7: [0068]braking torque Mbr caused by the
driver by braking, which depicts a braking torque variable with the
embodiment is lower or equal to a braking torque threshold value
Mbrs;

[0069]Eighth Criterion K8: [0070]the current spring paths zVL,
zVR, zHL, zHR at the chassis springs of the vehicle wheels
2.1 (HL), 2.2 (HR), 2.3 (VR), 2.4 (VL), which for example depicts a
spring path variable, are lower or equal to a spring path threshold value
zs; it is checked additionally if the amount of a difference spring
path variable, which is for example formed by the difference
|zHPVL-zHPVR| of the current spring paths zHPVL,
zHPVR especially high pass-filtered via a high pass is formed at the
two chassis springs of a vehicle axle, is smaller or equal to a
difference spring path threshold value Δzs

[0071]Ninth Criterion K9: [0072]a slip differential value, which is here
formed by the slip difference between two vehicle wheels is lower or
equal to a slip difference threshold value; a first slip difference
|λVL-λVR| is for example compared between the two
front wheels 2.3 (VR), 2.4 (VL) and a second slip difference
|λHL-λHR| between the two rear wheels 2.1 (HL), 2.2
(HR) with a front axle slip difference threshold value λvs or
a rear axle slip difference threshold value λvs:

[0072]|λHL-λHR|≦λHs

|λVL-λVR|≦λVs

[0073]It is determined via the logic block AND, if all of the eight
criteria K2 to K9 are fulfilled (that is, whether all inequalities given
in FIG. 3 are fulfilled and thus "true"). If so, the second flag is set
F2=1. On the other hand, if one or more the criteria K2 to K9 checked in
the validity block are not fulfilled, the second flag F2=0.

[0074]In a switch-off block OFF (FIG. 2, and shown in more detail in FIG.
4), one or more switch-off criteria K10, K11, K12 are considered. A third
flag F3 is set to F3=1, if at least one of the switch-off criteria is
fulfilled. The switch-off criteria checked with the embodiment described
here are:

[0081]If none of the switch-off criteria K10, K11, K12 is fulfilled, the
third flag F3 is set to F3=0. The switch-off criteria K10, K11, K12 are
interconnected to the third flag F3 in the or interconnection block OR.

[0082]Considering the three flags F1, F2, F3 and a fourth flag F4, the
intervention signal BES is determined in a logic block LOG, which is fed
back to an input of the logic block LOG as the fourth flag F4. In the
logic block, the values of the flags F1, F2, F3, F4, present in the
current method cycle, and also partially the values of the flags F1, F2,
F3, F4 from the previous method cycle n-1 are used for determining the
intervention signal BES. In the present case, the values of the first
flag F1, the second flag F2, and the fourth flag F4 from the previous
method are considered.

[0083]The following is valid as necessary conditions for an intervention
signal BES triggering a braking process: [0084]The third flag F3=0
(that is, none of the switch-off criteria K10, K11, K12 is fulfilled);
and [0085]the first flag F1=1, that is, the conditions defined in the
hysteresis block HYS have to be fulfilled.

[0086]In the current method cycle n, the intervention signal BES is
BES(n)=F4(n)=1. if one of the combinations occurring in the following
table occurs. Each row of the table corresponds to a combination of
conditions which triggers or maintains a braking operation in the
prevailing method cycle:

[0087]A braking process at one or more wheels is triggered or maintained
via the braking force activation device 4, if the intervention signal is
BES=1.

[0088]A new method cycle starts subsequently analogous to the
above-described method cycle. At the start of the first method cycle,
respective starting values F1(start), F2(start), F3(start) and F4(start)
are given as values of the flags F1, F2, F3, F4 for the previous method
cycle, so that the method can also work with the first method cycle
(e.g., when starting the vehicle). Such an approach is known with cyclic
methods. The start values can for example be given as follows:
F1(Start)=0, F2(Start)=0, F3(Start)=0 and F4(Start)=0.

[0089]The embodiment described here carries out a braking intervention as
chassis intervention to counteract the transverse dynamics disturbance.

[0090]Alternatively or in addition, the transverse dynamics disturbance
can also be compensated, at least partially, by other chassis
interventions: [0091]The servo torque of a servomotor (especially, an
electrical servo motor) for the vehicle steering system can be
influenced, so that the driver is supported when countersteering. The
servo-torque is directed in such a manner that the driver is prompted to
steer against the transverse dynamics disturbance. If the driver does not
hold the steering wheel, and if he complies with the servo torque of the
servo motor, a so-to-speak automatic countersteering takes place.
[0092]The wheel load of one or more wheels 2.1-2.4 of the vehicle 1 can
be changed, for example by the actuation of an active spring or damper
system associated with the respective wheel 2.1, 2.2, 2.3, 2.4, or an
active stabilisator of the vehicle. The wheel load of two wheels opposite
each other 2.1 (HL) and 2.3 (VR) or 2.2 (HR) and 2.4 (VL)b can be
increased with regard to the two other wheels 2.2 (HR) and 2.4 (VL) or
2.1 (HL) and 2.3 (VR). A transverse force is generated by the axle
geometry, especially the toe-in. Alternatively or in additional, the
wheel loads can also be reduced at two wheels diagonally opposite. This
transverse force can be used to compensate at least partially for the
transverse dynamics disturbance. [0093]Analogous to carrying out a
braking process, there is also the possibility to distribute the wheel
drive force unequally on the two vehicle sides, which can for example be
achieved by an actuatable axle differential. The wheel drive force can
thus be increased at one vehicle side and/or be reduced at the other. A
yaw movement is effected due to the to the unequal wheel drive forces on
both vehicle sides. This yaw movement takes place against the transverse
dynamics disturbance and can thus at least reduce this and compensate it
completely in the ideal case.

[0094]The foregoing disclosure has been set forth merely to illustrate the
invention and is not intended to be limiting. Since modifications of the
disclosed embodiments incorporating the spirit and substance of the
invention may occur to persons skilled in the art, the invention should
be construed to include everything within the scope of the appended
claims and equivalents thereof.